Transport Publication - TP 10038 E (2003)
Restricted Visibility
If you cannot see other vessels because of fog or bad weather reduce speed, sound your fog signal, proceed with extreme caution and be prepared to stop.
If you detect a vessel abeam or behind the beam by radar alone avoid turning toward the vessel if at all possible.
If you hear the foghorn of another vessel apparently forward of your beam, reduce your speed to the minimum needed to keep on course, be prepared to stop and navigate with extreme caution.
If you detect a vessel forward of the beam by radar alone, avoid altering course to port, except in cases of overtaking another vessel.